I was reading through this article about image pasting in Chrome and Firefox.

To recap, Firefox does not provide any information about the image pasted, the "paste" event handler gets a null clipboardData object.

To work around, one places an invisible contenteditable div in the DOM and always keeps it in focus, when stuff is pasted it triggers a timeout that checks the contents of the invisible div to grab an image handle.

Is there any way to hack stuff using magic iframes or what-not, short of replacing the textarea with a contenteditable div, to get paste-image-support in Firefox?

You can focus the content-editable div in the document.onpaste method. This should allow you to not force focus on that div the entire time.
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BuildstartedJan 4 '13 at 5:16

have you tried that? I wonder if its too late when you do that
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Sam SaffronJan 4 '13 at 6:56

I saw the trick being used on another site a while back. I'll see if I can find it if you'd like.
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BuildstartedJan 4 '13 at 21:54

1

I've recently made a unified interface to capture the pasted image on desktop browsers. github.com/layerssss/paste.js . It now support IE11, Firefox, Chrome. You guys might want to check it out.
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Michael YinNov 10 '14 at 4:53

The onpaste fires here because you have your contenteditable div and you can then tell firefox where to focus this clipboard data. (without having at least one contenteditable item the onpaste doesn't fire)

The clipboardData stuff is definitely working now, but is EMPTY when pasting images. It works fine for pasting image FILES though... Anyway, after playing with this for ... far too long, I've filed a bug against Firefox.
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JaykulJul 9 '13 at 6:21